Slip sliding away - testing in snow and ice
Slips, trips and falls at home, work and in public places can cause serious injury, lost productivity and major compensation claims. The risk of slipping increases where people walk in conditions of snow and ice. Such risk can often be greatest at entrance and exit points of buildings where partially melted snow
and ice creates a hazardous combination, made worse by the tendency of many people to relax attention when stepping inside from extreme external conditions.
Working direct with manufacturers and public and private institutions and companies, SATRA Technology Centre plays a key role in research and development to improve the slip resistance of footwear and floor surfaces. Thirty years ago SATRA designed and built the first prototype laboratory-based slip testing rig and developed the corresponding test method.
The slip rig can be set up to test on an ice surface, and SATRA has conducted fundamental research into the characteristics of slip between footwear and ice in a number of forms (frozen, frosted and smooth). While it is incorrect to claim that footwear
can be made non-slip, it is certainly the case that research and testing has allowed the global footwear industry to improve the slip resistance of footwear.
The risk of slip is present in a vast array of situations the whole year round and the development of slip resistance leads to the question when does slip resistance pose a comparable hazard to slip. SATRA has conducted research focused on the balance between translational movement (footwear sliding in a straight line across the floor surface) and rotational movement (footwear rotating left or right on a floor surface). Footwear requires a high translational coefficient of friction to minimise the risk of slipping, but low rotational friction to reduce the risk of leg and joint strains and breaks. If you can imagine a shoe sticking to the floor, if the strength of this 'stick' is so strong that it prevents the wearer from rotating the sole, then any sudden twist will put all the strain on the wearer's limbs and joints and not the usual friction/slip point between sole and floor. The potential injury could be just as severe as that caused by a slip.
Part of SATRA's research involves studded footwear used in various sports, where the design of cleats or studs is now technologically advanced. Quick acceleration and firm anchorage of the support foot when kicking, requires high traction. This is
achieved by increasing cleat length and the total area of the vertical leading face of the cleats so that resistance is increased as the stud ploughs into the turf. However, high twisting strains on knee and ankle joints can result if the sole of the boot and ground 'lock' together. The playing surface itself also contributes and stud design needs to follow any trend
towards, for example, a next generation of artificial surfaces.
As well as the construction of footwear and floor surfaces - for example stud and tread patterns and surface texture on floorings
– the materials used in products can make a significant difference to slip. Advances in materials science, innovative design, and further insights on the mechanisms of slip will offer
manufacturers and research organisations like SATRA more
opportunity to develop footwear and floor surfaces that are safer
across a wider variety of conditions.
SATRA Technology Centre